package common

import (
	"fmt"
	"net"
)

// In order for the IpPortTuple and the TcpTuple to be used as
// hashtable keys, they need to have a fixed size. This means the
// net.IP is problematic because it's internally represented as a slice.
// We're introducing the HashableIpPortTuple and the HashableTcpTuple
// types which are internally simple byte arrays.

const MaxIPPortTupleRawSize = 16 + 16 + 2 + 2

type HashableIPPortTuple [MaxIPPortTupleRawSize]byte

type IPPortTuple struct {
	IPLength         int
	SrcIP, DstIP     net.IP
	SrcPort, DstPort uint16

	raw    HashableIPPortTuple // Src_ip:Src_port:Dst_ip:Dst_port
	revRaw HashableIPPortTuple // Dst_ip:Dst_port:Src_ip:Src_port
}

func NewIPPortTuple(ipLength int, srcIP net.IP, srcPort uint16,
	dstIP net.IP, dstPort uint16) IPPortTuple {

	tuple := IPPortTuple{
		IPLength: ipLength,
		SrcIP:    srcIP,
		DstIP:    dstIP,
		SrcPort:  srcPort,
		DstPort:  dstPort,
	}
	tuple.ComputeHashebles()

	return tuple
}

func (t *IPPortTuple) ComputeHashebles() {
	copy(t.raw[0:16], t.SrcIP)
	copy(t.raw[16:18], []byte{byte(t.SrcPort >> 8), byte(t.SrcPort)})
	copy(t.raw[18:34], t.DstIP)
	copy(t.raw[34:36], []byte{byte(t.DstPort >> 8), byte(t.DstPort)})

	copy(t.revRaw[0:16], t.DstIP)
	copy(t.revRaw[16:18], []byte{byte(t.DstPort >> 8), byte(t.DstPort)})
	copy(t.revRaw[18:34], t.SrcIP)
	copy(t.revRaw[34:36], []byte{byte(t.SrcPort >> 8), byte(t.SrcPort)})
}

func (t *IPPortTuple) String() string {
	return fmt.Sprintf("IpPortTuple src[%s:%d] dst[%s:%d]",
		t.SrcIP.String(),
		t.SrcPort,
		t.DstIP.String(),
		t.DstPort)
}

// Hashable returns a hashable value that uniquely identifies
// the IP-port tuple.
func (t *IPPortTuple) Hashable() HashableIPPortTuple {
	return t.raw
}

// Hashable returns a hashable value that uniquely identifies
// the IP-port tuple after swapping the source and destination.
func (t *IPPortTuple) RevHashable() HashableIPPortTuple {
	return t.revRaw
}

const MaxTCPTupleRawSize = 16 + 16 + 2 + 2 + 4

type HashableTCPTuple [MaxTCPTupleRawSize]byte

type TCPTuple struct {
	IPLength         int
	SrcIP, DstIP     net.IP
	SrcPort, DstPort uint16
	StreamID         uint32

	raw HashableTCPTuple // Src_ip:Src_port:Dst_ip:Dst_port:stream_id
}

func TCPTupleFromIPPort(t *IPPortTuple, streamID uint32) TCPTuple {
	tuple := TCPTuple{
		IPLength: t.IPLength,
		SrcIP:    t.SrcIP,
		DstIP:    t.DstIP,
		SrcPort:  t.SrcPort,
		DstPort:  t.DstPort,
		StreamID: streamID,
	}
	tuple.ComputeHashebles()

	return tuple
}

func (t *TCPTuple) ComputeHashebles() {
	copy(t.raw[0:16], t.SrcIP)
	copy(t.raw[16:18], []byte{byte(t.SrcPort >> 8), byte(t.SrcPort)})
	copy(t.raw[18:34], t.DstIP)
	copy(t.raw[34:36], []byte{byte(t.DstPort >> 8), byte(t.DstPort)})
	copy(t.raw[36:40], []byte{byte(t.StreamID >> 24), byte(t.StreamID >> 16),
		byte(t.StreamID >> 8), byte(t.StreamID)})
}

func (t TCPTuple) String() string {
	return fmt.Sprintf("TcpTuple src[%s:%d] dst[%s:%d] stream_id[%d]",
		t.SrcIP.String(),
		t.SrcPort,
		t.DstIP.String(),
		t.DstPort,
		t.StreamID)
}

// Returns a pointer to the equivalent IpPortTuple.
func (t TCPTuple) IPPort() *IPPortTuple {
	ipport := NewIPPortTuple(t.IPLength, t.SrcIP, t.SrcPort,
		t.DstIP, t.DstPort)
	return &ipport
}

// Hashable() returns a hashable value that uniquely identifies
// the TCP tuple.
func (t *TCPTuple) Hashable() HashableTCPTuple {
	return t.raw
}

// Source and destination process names, as found by the proc module.
type CmdlineTuple struct {
	Src, Dst []byte
}
